Solamargine, solasonine, N-hydroxyrobustine and a new glycoalkaloid, N-hydroxysolamargine, has been isolated from the leaves of Solanum robustum, the structure of which has been elucidated as (25R)-3 beta-{O-alpha-L-rhamnopyranosyl-(1 --> 2)-O-[alpha-L-rhamnopyranosyl-(1 --> 4)]-beta-D-glucopyranosyloxy}-22 alpha N-spiroso-5-en-N-ol.